1. Field of the Invention
The present invention relates to a dental handpiece having a gripping sleeve, a drive aggregate arranged in the handpiece for a dental treatment work tool retained in a head portion, and which includes its own built-in electrical light source. The light source, together with conduits for supply media, is arranged within an intermediate member which is exchangeably mounted between the gripping sleeve and the end member of a supply hose for the supply media for the handpiece The light from the light source, with the aid of strand-like light conductors arranged interiorly of the handpiece, is conducted to the region of the handpiece head portion and exits there from the gripping sleeve directed towards the tooth treatment worktool, and in which the light source can be switched on and off through the intermediary of a compressed air-driven pneumatic switch device.
2. Discussion of the Prior Art
A dental handpiece of that type has become known from the sales brochure HP013-879-2011 issued by the firm Midwest American. In order to change over a dental treatment unit, whose handpieces are normally not provided with its own built-in light source of the above mentioned type, into a unit in which a light source is built into the handpiece, it has been found to be necessary to exchange the collective connections on the handpiece and the entire supply hose. However, inasmuch as a large number of handpiece connector couplings and supply hoses are present which are differently constructed and are of different lengths, such a changeover causes considerable problems. Moreover, frequently there must be provided an additional suitable connection for the electrical conduits. In addition, above all there must also always be considered that for possibly occuring defects or disturbances in the light installation due to the separate arrangement of the intermediate member and the pneumatic switch device, inspections must be conducted at a number of locations, which renders the overcoming of this drawback quite complex and time-consuming.
Furthermore, disclosed in U.S. Pat. No. 3,634,938 is a similar dental handpiece in which there is also arranged between the gripping sleeve and the end body of the supply hose, an interchangeable intermediate member which contains the light source. This intermediate member always evidences a diameter which is large in comparison with the gripping sleeve, and which is quite unwieldly with respect to the manipulation of the handpiece, since at its end surfaces there are provided the connections for the strand-like light conductor, which projects at least partially outwardly of the gripping sleeve and which are provided for the electrical conduit for the light source. Moreover, required for this electrical conduit is a separate cable which leads to a transformer located remote from the handpiece and which, in turn, has a hand-operated switch connected ahead thereof in the power supply.
In a handpiece of that kind it is also relatively easy to construct the intermediate member with the light source in order to place it into operation; however, this large sized intermediate member, during manipulation of the handpiece, is disturbingly located in the crook between the thumb and the index finger. Moreover, in placing the handpiece into operation, the lighting installation of the handpiece must be switched on by means of a separate handswitch, which is cumbersome. The primary disadvantage lies in that also in this known handpiece, for possible disruptions in the light installation, inspections must be undertaken at a number of locations, which is extremely time consuming.